Streptomyces aridus sp. nov., isolated from a high altitude Atacama Desert soil and emended description of Streptomyces noboritoensis Isono et al. 1957

Abstract

A polyphasic study was undertaken to determine the taxonomic status of a Streptomyces strain which had been isolated from a high altitude Atacama Desert soil and shown to have bioactive properties. The strain, isolate H9^T, was found to have chemotaxonomic, cultural and morphological properties that place it in the genus Streptomyces. 16S rRNA gene sequence analyses showed that the isolate forms a distinct branch at the periphery of a well-delineated subclade in the Streptomyces 16S rRNA gene tree together with the type strains of Streptomyces crystallinus, Streptomyces melanogenes and Streptomyces noboritoensis. Multi-locus sequence analysis (MLSA) based on five house-keeping gene alleles showed that isolate H9^T is closely related to the latter two type strains and to Streptomyces polyantibioticus NRRL B-24448^T. The isolate was distinguished readily from the type strains of S. melanogenes, S. noboritoensis and S. polyantibioticus using a combination of phenotypic properties. Consequently, the isolate is considered to represent a new species of Streptomyces for which the name Streptomyces aridus sp. nov. is proposed; the type strain is H9^T (=NCIMB 14965^T=NRRL B65268^T). In addition, the MLSA and phenotypic data show that the S. melanogenes and S. noboritoensis type strains belong to a single species, it is proposed that S. melanogenes be recognised as a heterotypic synonym of S. noboritoensis for which an emended description is given.

Keywords: Aridus; Atacama Desert; Polyphasic taxonomy; Streptomyces.

Fig. 1

Scanning electron micrograph of isolate H9^T showing spiral chains of smooth surfaced spores following growth on oatmeal agar at 28 °C for 10 days. Bar 1 µm

Fig. 2

Neighbour-joining phylogenetic tree based on nearly complete 16S rRNA gene sequences (1329–1425 nucleotides) showing relationships between isolate H9^T and closely related type strains of Streptomyces species. Asterisks indicate branches of the tree that were recovered using the maximum-likelihood (ML) and maximum-parsimony tree-making methods. ML indicates branches of the tree that were also supported by this algorithm. Numbers at the modes indicate levels of bootstrap support based on a neighbour-joining analysis of 1000 resampled datasets, only values above 50% are given. The scale bar indicates 0.005 substitutions per nucleotide position

Fig. 3

Streptomyces sub-tree derived from the phylogenetic tree inferred from concatenated partial sequences of the house-keeping genes atpD, gyrB, recA, rpoB and trpB using the maximum-likelihood method based on the General Time Reversible model. The final dataset consisted of 2622 positions and 706 strains. Percentages at the nodes represent levels of bootstrap support from 1000 resampled datasets, values less than 60% are not shown. The proposed new species is indicated in bold. Bar, equals number of substitutions per site